This project will study the etiology of facial clefting in the minority patients served by Rancho Los Amigos Hospital in Los Angeles County, California. The expected sample is 205 Hispanic families, 32 black families, 13 Oriental families and 91 Caucasian families. Data on patients born between the years 1971 and 1981 and operated on for cleft lip with or without cleft palate or cleft palate alone will be assembled in computer files. Data will include sex, race, birthdate, anatomical details of the cleft, dermatoglyphics, drug or illness exposure during pregnancy, and detailed family history of clefting and other malformations. The patients are followed for 16 years in the clinic and a high percentage will be available for participation in this study through their follow-up visits. The study will focus on three areas: epidemiology, dermatoglyphics and genetics. (1) The entire sample will be used for epidemiological studies to characterize the types and frequencies of clefts in the Hispanics. In addition, hypotheses concerning the association of specific factors with clefting will be tested, e.g. sex, season of birth, parental age, etc. (2) Dermatoglyphic patterns will be analyzed to test for differences between clefted individuals and their normal siblings including the hypothesis of increased asymmetry in clefted individuals. (3) The entire sample nuclear family data will be subjected to segregation analysis to test the genetic hypotheses of a single major gene contributing to the etiology of cleft lip/palate in all or some of the families. The multifactorial threshold model will be tested rigorously. A subsample of multigenerational families with multiple affected individuals will be used in pedigree analysis to test the same hypotheses without having to pool families, i.e. assume a homogeneous etiology. In addition, these large pedigrees will be blood typed for 28 gene markers and gene linkage analyses will be used to specifically identify the major loci contributing to facial clefting in this population.